The Taxonomy of Touch (or Hard-Smooth-Cool-Dry)

For sight, we learn Red Orange Yellow Green Blue Purple. For taste, we learn Salty Sour Sweet Bitter. For sound, we learn Volume and Pitch, Rhythm and Timbre. But for touch? What are those basic categories of how things feel that I can teach my kids — and myself? What is that taxonomy of touch?

To my surprise, after hours searching the internet over the past months, I haven’t been able to find a simple table. So here’s what I’ve come up with, after a few failed starts. If I’ve done it right, it should hopefully feel obvious:

There are 2 main ways that things feel based on what they are:

Hard or Soft
Smooth or Textured

And there are 2 main ways that things feel based on their current state:

Wet or Dry
Cool or Warm

Altogether then, there are 16 (2x2x2x2) ways that most objects feel at any moment. Of course, like Red-Orange-Yellow or Salty-Sweet, simple categories hardly capture the nuances of the color of wood (yellow?) or the flavor of a slice of bread (salty?). But what having this simple taxonomy does is unlock an awareness of what on earth we are touching, and where we may be sensation-deprived.

The touch I refer to in my taxonomy is where you run your finger over an object to feel what’s there. Since your touch nerves detect vibration, moving your finger around on the surface helps you feel it better than just plonking your finger down once.

Now catalogue what textures you have felt the past 5 minutes. Actually what are you feeling now? I would guess it’s Hard-Smooth-Cool-Dry. In fact, I would guess a majority of the things that you touch (other than your own face or hair) are Hard-Smooth-Cool-Dry. Our phones, our keyboards, or cooking and eating utensils, doorknobs, buttons — most of the tools and implements of our lives are Hard-Smooth-Cool-Dry.

Think for a moment of what objects you touch that aren’t Hard-Smooth-Cool-Dry. Likely it will be either food or textiles : maybe you are wearing some cotton or synthetic material that is Soft-Smooth-Warm-Dry, or just ate a slice of pear, which was Soft-Smooth-Cool-Wet.

Now go outside. Here the challenge is reversed: it’s almost impossible to find something that is Hard-Smooth-Cool-Dry. Run your fingers over the tree bark that is hard but textured. The leaves that are smooth but soft. The grass that is soft and textured, cool and wet. The mud, the small pebbles. The only thing in nature that I could find that is Hard-Smooth-Cool-Dry are large sea-worn stones like on the beaches of Brighton.

Human history is a story of tools, and as we’ve moved through history, those tools seem to have become uniform in how they feel, from arrow heads on. Maybe it’s because of production techniques, materials that last, or some sense that things that are Hard-Smooth-Cool-Dry are modern. Maybe it’s the fear of germs, which lurk on surfaces we can’t clean easily, like those high pile rugs we won’t get until our kids are older or those sequined dresses you can’t tumble dry. Isn’t weird that soft and textured items feel cosier than hard and smooth things, but a cup of tea, the pinnacle of British comfort, is served in hard, smooth mugs?

We know deep down that there’s a simple joy of touching things which are in the outer reaches of my taxonomy of touch, toward the Soft-Textured-Warm-Wet corner. How much of the foods we crave as guilty pleasures are those we eat with our sensation-seeking hands — the snack foods your fingers feel out of the crinkly bag, the soft roll on a ham and cheese sandwich, the juicy cool watermelon which drips down your wrist, the still warm pieces of turkey you pick off the bone when no one’s looking? How much more joy would we have in life if we ate more of our food with our fingers?

2020 has been a tough year. And I can’t help wonder, looking back, if it’s been worse because we’ve been told not to touch things. Not to touch our faces even, our friends, doorknobs and elevator buttons, the sticky squishy rubber buttons of a pub’s PIN code reader, our neighbor’s new foofy puppy.

As we go into 2021, I have a resolution : to touch more objects that are not just Hard, Smooth, Cool and Dry. And to be more mindful in those moments of how what I am touching feels.

So maybe 2021 is the time to buy that Etsy knitted sweater for my tea mug, to eat rice with my fingers, and finally, a year behind the curve, to learn to knead my own sourdough bread.

All the best for safe, healthy 2021! And thanks, as always, for staying in touch.


p.s. If you are interested in the field of touch, let me know! I’ve spent some of my non-existent free time this year learning about the fascinating subject of touch, most of which didn’t make it into this blog. I have some cool findings and even more outstanding questions across the many disciplines this subject ‘touches’: the biology (can we learn to get better at touch? does it change as we age?), materials properties (how does the physical properties of a surface affect how we feel it?), virtual reality and haptics technology (will we be able to feel objects in VR? how? how would it be used?), product design and packaging (what are the rules for a good tactile experience?), role of touch in art (how do artists use touch as a medium and how would you even display it?), standards for touch in product design and manufacturing (a company called SynTouch seems to have identified a technical definition for touch; are there others?), transmission of touch data (how could you record and send a texture to someone else the way we do with voice?), role of touch in dreaming (why don’t we dream of touch?), history and anthropology (what % of time do we spend touching different surfaces and how has that changed over time?), … and many more. Love to hear your thoughts too!